Add pre-push subcommand and update dependencies

[fasterthanlime]

Summary

• Implements pre-push subcommand to run targeted checks on modified crates (resolves Optimize pre-commit/pre-push hooks to only run on touched crates facet#1247)
• Updates dependencies to latest versions (merges PRs Update Rust crate log to v0.4.29 - autoclosed #10, Update Rust crate fs-err to v3.2.0 - autoclosed #11, Update Rust crate owo-colors to v4.2.3 - autoclosed #13)
• Updates GitHub Actions to latest versions (merges PRs Update github/codeql-action action to v4 - autoclosed #12, Update actions/checkout action to v6 - autoclosed #14)
• Adds Windows compatibility (merges PR work on Windows #9)

Changes

New pre-push subcommand

The pre-push subcommand runs checks only on crates affected by changes:

• Detects changed files since merge-base with origin/main
• Identifies affected crates from file paths
• Runs cargo clippy -p <crate>, cargo test -p <crate>, and cargo test --doc -p <crate> for each affected crate
• Provides colorized output showing which checks passed/failed

Windows compatibility

• Makes executable bit handling conditional on Unix platforms with #[cfg(unix)]
• Allows the tool to work on Windows where executable bits don't exist
• Credits: @boringcactus

Dependency updates

• fs-err: 3.1.0 → 3.2.0
• log: 0.4.27 → 0.4.29
• owo-colors: 4.2.1 → 4.2.3

GitHub Actions updates

• actions/checkout: v5 → v6
• github/codeql-action: v3 → v4

Test plan

• Build succeeds: cargo build
• Tests pass: cargo test
• Clippy passes: cargo clippy -- -D warnings
• Verify pre-push subcommand works: cargo run -- pre-push (requires changes in a git branch)